Question

The marks scored by a student in five subjects are 80,75,62,50 and 91. How much should he score in the 6th subject to make his average 74?

Answer 1

He has to score 86.

SOLUTION:

Let it be x
sum of scores of 5 subjects=358
Average=(sum of 6 subjects)/(No. of subjects)
no. of subjects=6
Average=(358+x)/6
It is 74 as per given data
(358+x)/6 =74
358+x=444
x=444-358
x=86. That's it!!!

Answer 2

The student must score 86 marks in the sixth subject to take his average to 74.

      Let the marks to be scored in sixth subject be x.

1. Total of all subject marks is 80+75+62+50+91+x = 358 + x
2. The average of the marks in total subjects would be (358+x)/6 =  59.67 +x/6
3. But the average of the marks must equal to 74.
4. Equating both the equations => 59.67+x/6 = 74
5. x/6 = 14.33 => x= 86.
6. Hence, the student must score 86 marks.